1. Field of the Invention
The present invention relates generally to a liquid crystal display device, and more particularly to a construction which prevents the flow of a seal element that attaches a pair of substrates to a pixel area.
2. Description of the Related Art
Liquid crystal display devices are widely used as display devices for various kinds of equipment such as personal computers, OA equipments, and TV sets because the display devices have many advantages such as lightness, compactness and low power consumption. In recent years, the liquid crystal display device is also used in a mobile terminal equipment such as a mobile phone, a car navigation device and a game player.
A liquid crystal display device includes a liquid crystal display panel having a liquid crystal layer sandwiched between an array substrate and a counter substrate with a seal element. The liquid crystal display panel includes a rectangular shaped active area for displaying an image, which is surrounded by the seal element.
In such a liquid crystal display device, the seal element flows out to the active area when the array substrate and the counter substrate are attached with the seal element. In particular, the seal element tends to flow along a small gap area between the opposed substrates by a capillary action. A wiring drawn out of the active area crosses the seal element so that the seal element tends to spread by flowing on the wiring located at the small gap area. The flowing out seal element may result in a display defect.
Though it is thought to make a gap between the active area and the seal element larger, such an approach runs counter to the current requirement for a small outside dimension. In order to solve this problem, Japan Laid Open Patent application 2006-126756 discloses a technology in which a wall shaped spacer is provided at a way point of the wiring layer so as to cross the wiring layer which is drawn out of a pixel area. Further, the above patent application discloses a technology in which the drawn out wiring layer is provided with a crank area to weaken the flowing strength of the seal element, and a scraped region with a belt shape is provided on a color filter layer formed on the counter substrate corresponding to the wiring layer to suppress the spread of the seal element by making the gap between the substrates large.
On the other hand, Japan Laid Open Patent Application 1999-52394 discloses a technology addressed to a problem when a light curing resin is used as the seal element. In the technology, incomplete hardening is caused due to shadowing of ultraviolet light, which is necessary to harden the seal element provided at the intersection with the wiring layer, by the wiring. Some slits are formed in the wiring layer at the overlapped portions with the seal element.
In the recent liquid crystal display device, the gap between the array substrate and the counter substrate becomes smaller and smaller so as to achieve a short response time and a wide view angle, which results in such construction that the seal element tends to flow easily. Further, the active area is arranged relatively close to the seal element to meet the requirement for narrow frame so as to make the outside dimension small.
As shown in the Japan Laid Open Patent Application 2006-126756, a dam shaped spacer formed simultaneously with a columnar spacer by using a light curing resign, has generally a taper shape in cross section and the area of a base side of the spacer where the spacer is formed is larger than that of a tip side. Therefore a larger area, which prevents obtaining a narrow frame, is needed to provide the dam shaped spacer. Further, since the dam shaped spacer has a height such that the spacer almost contacts to the counter substrate, the dam shaped spacer becomes a bar to injection of a liquid crystal material.
The seal element is applied so as to surround the active area. In the process for applying the seal element, the applying speed is lowered at the corner of the liquid crystal display panel, which results in an accumulation of the seal element. A power supply line of the array substrate is connected to a common electrode on the counter substrate through a conductive element at the corner of the liquid crystal display panel. The power supply line crosses the seal element and extends to the space between the active area and the seal element. Since the power supply line has a relatively larger width than that of a gate line or a source line, the accumulated seal element tends to flow into the active area along the power supply line.